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Optimization of a plasma immersion ion implantation process for shallow junctions in silicon

DSpace at IIT Bombay

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Title Optimization of a plasma immersion ion implantation process for shallow junctions in silicon
 
Creator RAY, A
NORI, R
BHATT, P
LODHA, S
PINTO, R
RAO, VR
JOMARD, F
NEUMANN-SPALLART, M
 
Subject ENERGY-DISTRIBUTION
DISCHARGE
 
Description A plasma immersion ion implantation (PIII) process has been developed for realizing shallow doping profiles of phosphorus and boron in silicon using an in-house built dual chamber cluster tool. High Si etch rates observed in a 5% PH3 in H-2 plasma have been ascribed to high concentration of H(alpha) radicals. Therefore, subsequent work was carried out with 5% PH3 in He, leading to much smaller etch rates. By optical emission spectroscopy, the radical species H(alpha), PH*(2), and PH* have been identified. The concentration of all three species increased with pressure. Also, ion concentrations increased with pressure as evidenced by Langmuir data, with a maximum occurring at 0.12 mbar. The duty cycle of pulsed DC bias has a significant bearing on both the implantation and the etching process as it controls the leakage of positive charge collected at the surface of the silicon wafer during pulse on-time generated primarily due to secondary electron emission. The P implant process was optimized for a duty cycle of 10% or less at a pressure of 0.12 mbar with implant times as low as 30 s. Secondary ion mass spectroscopy showed a P dopant depth of 145 nm after rapid thermal annealing (RTA) at 950 degrees C for 5 s, resulting in a sheet resistance of 77 Omega/square. Si n(+)/p diodes fabricated with phosphorus implantation using optimized PIII and RTA conditions exhibit J(on)/J(off) > 10(6) with an ideality factor of nearly 1.2. Using similar conditions, shallow doping profiles of B in silicon have also been realized. (C) 2014 American Vacuum Society.
 
Publisher A V S AMER INST PHYSICS
 
Date 2014-12-28T12:38:40Z
2014-12-28T12:38:40Z
2014
 
Type Article
 
Identifier JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, 32(6)
0734-2101
1520-8559
http://dx.doi.org/10.1116/1.4896756
http://dspace.library.iitb.ac.in/jspui/handle/100/16562
 
Language English